Biodegradation of Phenolic Compounds in Creosote Treated Wood Waste by a Composting Microbial Culture Augmented with the Fungus &lt;i&gt;Thermoascus aurantiacus&lt;/i&gt;

Ghaly Ghaly

doi:10.3844/ajbbsp.2011.90.103

Abstract

Problem statement: Creosote is used as a wood preservative and water proof agent in railway sleepers, utility poles, buildings foundations and fences and garden furniture. It is a mixture of over 300 hydrocarbons which include 75% polycyclic aromatic hydrocarbons, 2-17% phenolic compounds and 10-18% heterocyclic organic compounds. Exposure to creosote may result in several health problems including damage to kidney, liver, eyes and skin. Potential contamination of soil and water exist from creosote treated wood from construction and demolition sites. Approach: The possibility of using an invessel composting process augmented with the ascomycetous fungus Thermoascus aurantiacus as a mesophilic/thermophilic bioremediation option for the degradation of phenolic compounds in creosote treated wood waste was evaluated. Results: The temperatures of bioremediation process reached thermophilic phase and the mesophilic and thermophilic lag phases were clearly identified. The moisture content decreased significantly indicating that the water produced by microbial respiration did not compensate for the water lost as vapor with the exhaust gases. Initial increases in pH due to the breakdown of organic nitrogen to ammonium and final drop in pH due to the formation of organic acids and the loss of ammonium with the exhaust gases in the latter stage were observed. Different degradation rates were observed in the mesophilic and thermophilic stages of composting. The control experiment achieved higher reductions of volatile solids, total carbon and TKN and higher degradation of phenolic compounds, cellulose and lignin, indicating a higher level of activity of microorganisms during the composting process compared with the inoculated experimental trial. The stability and maturity of the product of the control experiment were also better than those of the product from the inoculated experimental trial. Conclusion: The inoculation of the cellulolytic-thermophilic fungus Thermoascus aurantiacus did not accelerate the bioremediation process in degrading phenolic compounds and the fungus may have inhibited the growth and metabolic activities of composting organisms.

Highlights

Used in railway sleepers, utility poles, buildings foundations, building fences, bridges stakes for Creosote is distilled from crude coke oven tar agricultural and fruit products, garden furniture and consisting of around 75% of Polycyclic Aromatic outdoor recreational facilities in parks (CICAD, 2004; Hydrocarbons (PAHs), 2-17% phenolic compounds, Ikarashi et al, 2005)
The main aim of this study was to evaluate the possibility of using a composting process augmented with the ascomycetous fungus Thermoascus aurantiacus as a bioremediation option to facilitate the degradation of phenolic compounds in creosote treated wood waste
The decreased moisture content was due to the fact that the loss of moisture with the exhaust gas was higher than the moisture produced by metabolic activity as a result of declining bioavailable carbon

Summary

Introduction

Used in railway sleepers, utility poles, buildings foundations, building fences, bridges stakes for Creosote is distilled from crude coke oven tar agricultural and fruit products, garden furniture and consisting of around 75% of Polycyclic Aromatic outdoor recreational facilities in parks (CICAD, 2004; Hydrocarbons (PAHs), 2-17% phenolic compounds, Ikarashi et al, 2005). Because of different sources carcinogenic and genotoxic potentials due to the and preparation procedures in manufacturing processes, presence of PAHs as the main component of creosote the components of creosote may vary in concentration (ATSDR, 2002; CICAD, 2004). Creosote is widely contained in creosote are carcinogens and are toxic used as a preservative of wood products and water- to aquatic living creatures (CICAD, 2004). Because of proofing agent (Bedient et al, 1984; CEPA, 1994; its toxicity, creosote-treated wood does not degrade ATSDR, 2002). Creosote-treated wood has been widely in the environment and requires special disposal. The pollutants contained in the creosote-treated wood carried out in a specially designed multiple bioreactor waste are barriers to its use as landfill cover due to composting/bioremediation system (Fig. 1). Three potential migration of contaminants into ground water. bioreactors were horizontally fastened into a main

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